In the field of solar energy, conventional photovoltaic panels are used to generate electricity from sunlight. Conventional photovoltaic panels consist of arrays of photovoltaic cells, with each cell consisting of a semiconductor (e.g. monocrystalline silicon or polycrystalline silicon) substrate. The photovoltaic cells collect the solar energy and convert the solar energy into an electric current, where the power output from such conventional photovoltaic panels is a direct function of the total substrate area of the array. As a result, sizeable arrays of large, expensive semiconductor substrates are typically needed to generate sufficient electrical output.
There has been research and product development for many alternative methods of harvesting the energy from the sun to produce electric energy. In the field of concentrated photovoltaics (CPV), the need for large semiconductor substrates can be substantially reduced by concentrating solar light with optical elements, such as lenses and reflectors. The optical elements collect light over a wide surface area and direct the light towards a photovoltaic cell of substantially smaller surface area. The optical elements can be made of inexpensive materials such as glass or polymers to achieve competitive prices, and the photovoltaic cell is typically a high efficiency multi-junction cell for improving efficiency.
U.S. Patent Application Publication No. 2008/0271776 A1 to Morgan describes a solar energy system that uses a light-guide solar panel (LGSP) to trap light inside a transparent panel and propagate the light to one of the panel edges for harvesting by a solar energy collector such as a photovoltaic cell. This technology eliminates the depth requirements inherent in traditional concentrated photovoltaic solar energy systems.
It has long been considered desirable to integrate photovoltaic technology into commercial and residential buildings, however, to date, such systems have been generally limited to conventional PV systems, which absorb or block all incoming direct and diffuse light.
Since CPV systems can be made of transparent materials, capable of transmitting diffuse light to the inside of a building, it is desirable to develop a system which would could be used in construction and placed over windows, for example, to allow diffuse light to enter, while direct sunlight is concentrated by the panels. It is also desirable to integrate illumination capabilities into these panels, such that they can act as illumination systems when there is no sunlight. It is therefore an object at least to provide a novel concentrated photovoltaic and illumination panel.
U.S. Pat. No. 9,151,879 to Boer et al. describes a building-integrated photovoltaic system having a cylindrical lens array used in combination with strip solar cells and lateral displacement tracking systems, permitting diffuse light to pass through to the interior of the building, where the strip solar cells may absorb direct light and convert it to electricity. The system described by Boer uses optics lenses that focus light directly onto the strip solar cells, adding the requirement of a frame to hold the components apart from each other such that the solar strips are positioned at the depth of the focus of the lenses.
Improvements are generally desired, as well as useful integration of illumination technology with scattering optics. It is therefore an object at least to provide a novel concentration photovoltaic and illumination panel.